Electrical connectors are commonly used for attaching electrical conductors, cables, wires, electrical metal tubing (EMT) or the like to an electric box, e.g. a junction box, outlet box, switch box, fuse box, or other similar type of electric box or panel. Such known electrical connectors are either of a type that are secured to an electric box by a threaded lock nut or by means of a conventional circular snap fit retaining ring of the type disclosed in U.S. Pat. Nos. 6,860,758; 6,444,907; 5,189,258; 5,266,050; 5,171,164; 2,744,769 and 1,483,218 for example. Reference is also made to U.S. Pat. No. 6,768,057 which is directed to a right angle type connector formed of a pair of sheet metal stampings fitted together and secured to an electrical box with a snap fit arrangement.
Also known are connectors formed as connector caps which are adapted to be fitted over the end of a conductor, cable or wires, such as disclosed in U.S. Pat. No. 4,880,387. Various other known efforts to facilitate the connection of an electrical conductor to an electric box are evidenced by U.S. Pat. Nos. 6,043,432; 6,080,933; 6,114,630; 6,133,529; 6,194,661; 6,335,488; 6,352,439; 6,355,884; 6,444,907; 6,555,750; 6,604,400; 6,670,553; 6,737,584; 6,682,355; 6,780,029 and 6,849,803.
Notwithstanding the extensive background relating to electrical connectors, continuing efforts are being made to improve, simplify and/or reduce the cost and/or complexity of the known connectors in an effort to advance the electrical connector art. This disclosure is directed to such efforts.
In particular, difficulties have arisen with electrical connectors that snap-fit or push-in to electrical boxes. Often due to the reduced contact surface area there is reduced continuity or conductivity between the electrical connector and electrical box or junction box. Therefore, there may be inadequate bonding or grounding or a voltage drop across the connected electrical connector that may be excessive or higher than industrial standards would permit. Typically, snap-fit or push-in electrical connectors have portions that are made of spring steel that are plated with zinc or zinc alloy for corrosion resistance. The bodies of electrical connectors are typically cast from a zinc alloy. Due to the different contact points in a snap-fit or push-in electrical connector electrical continuity may be affected and substantially reduced. In some snap-fit or push-in electrical connectors industrial standards related to permissible voltage drop across the electrical connector may not be met.
Efforts have been made to improve continuity in snap-fit or push-in electrical connectors. Nearly all of these efforts have been directed to increasing contact surface area. For example, U.S. Pat. No. 6,709,280 entitled “Fitting with Improved Continuity” issuing Mar. 23, 2004 to Gretz. Therein disclosed is a fitting for connecting a cable to an electrically conducting junction box having a sloped grounding tang in which the downward slope causes the fitting to be drawn tightly against the junction box wall. Another fitting is disclosed in U.S. Pat. No. 6,780,029 entitled “High Continuity Electrical Fitting” issuing Aug. 24, 2004 to Gretz. Therein disclosed is a fitting for connecting a cable to an electrically conducting junction box that has larger grounding tangs providing much greater surface contact area, thereby improving continuity and lowing millivolt drop.
While these prior techniques improve continuity they have done so by increasing surface area contact. While this may provide some improvement in continuity, there is a limit to the increase surface area contact that can be obtained in an electrical connector or fitting. Therefore, there is a need for a different approach in obtaining improved continuity or conductivity between the electrical conductor or fitting, the electrical box, and the cable.